My overall experience with both stock and aftermarket chain tensioners has been a complete headache. I can't even estimate how many hours of my life I've wasted messing with em.
THE STOCK ONE - well...its a spoke killer from **** (could have easily killed me probably too...) After replacing two rear rims i decided it was time to try something else.
THE SPRING/SPROCKET ONE - I started hunting around on Amazon for something better. All the reviews I read said to get one with a spring and a sprocket, so I got this one -https://
www.amazon.com/gp/aw/d/B07QJBSBYJ/ref=ya_aw_od_pi?ie=UTF8&psc=1 I was trying to be as frugal as possible, $26 bucks aint terrible. Wish I would have spent more. This one is total junk. I run a #41 chain instead of the stock 415, maybe that has something to do with it, I don't know. I had to remove the master link, and even after that the chain would still rub. I ended up bolting it on the outside of the clutch cover and using some extra spacers to get the sprocket extended to the chain, but even this was a complete fail. I sent that POS right back to China and got my money back.
THE ANSWER - aside from not using one, home made chain tensioners are the best. Your imagination is the limit, and it's built for YOUR bike, not a wide range of bikes that may or may not work well on yours. I spent $25 bucks on the junk one, think I spent $7 making this and it's far superior. $2 for a pair of 1980's roller skates at Goodwill, and $5 for u bolts and hardware. The 1/4" piece of aluminum I had leftover from another project. Since I put it on the bike, I have yet to have to mess with it or do any adjustments of any kind. The one I'm making for my new build will be similar, except I'm using steel instead of aluminum, and welding it directly to the frame (eliminate those ugly u bolts, and my weird mis-mached washers ).
One final thought on the stock tensioner is that they are not all created equal. The one that came with my first kit was terrible, pure trouble from day one. Quite the contrary, the stock one that came with my new kit has been great, it's built much better, and 4 bolts secure it to the frame instead of just two. I'm only replacing it because its permanently ingraved in my brain how quickly it can screw up your ride, and...because I can... That's my two cents worth anyway.